From: Felipe Balbi <balbi@ti.com>
Subject: Re: AM335x BeagleBone SPI Issues
Date: Mon, 10 Dec 2012 15:53:37 +0200
Message-ID: <20121210135337.GA10219@arwen.pp.htv.fi>
References: <50C5E23D.5040605@communistcode.co.uk>
Reply-To: <balbi@ti.com>
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In-Reply-To: <50C5E23D.5040605@communistcode.co.uk>
Sender: linux-omap-owner@vger.kernel.org
To: Jack Mitchell <ml@communistcode.co.uk>
Cc: linux-omap@vger.kernel.org

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Hi,

On Mon, Dec 10, 2012 at 01:23:09PM +0000, Jack Mitchell wrote:
> Hi,
>=20
> I am currently having issues with the SPI driver on the beaglebone
> using the 3.7-rc8 kernel[1]. I have probed the SPI pins and I have
> found that writing works however reading doesn't. When using DMA the
> program seems to lock hard and no data is sent on the bus. I am
> testing the bus using spidev and the spidev_test[2] application,
> however I first came across spi issues with a custom spi driver which
> stopped working when I transitioned from 3.2-psp to 3.7-rc8.
>=20
> The current output I am seeing from the spidev_test program is just a
> series of 0x00 data, which looks to me like no data is getting in at
> all. The spidev_test program is not using DMA as the buffer size is
> too low, so I forced the dma on when buffer size is > 1 and the
> program hangs hard with the system still responding to other
> commands.I have briged the pins 18 and 21 on the BeagleBone P9
> header.
>=20
> Has anyone seen issues like this, or if not if someone could please
> test the latest 3.7-rc8 from [1] and let me know if it works for them
> and the issue is at my end.
>=20
> To get spidev working with devicetree I applied the patch from [3]
> and changed the dtb as in the patch pasted below.
>=20
> [1] https://github.com/beagleboard/kernel/tree/3.7
> [2] http://lxr.linux.no/#linux+v3.6.9/Documentation/spi/spidev_test.c
> [3] http://www.mail-archive.com/spi-devel-general@lists.sourceforge.net/m=
sg09958.html

do you have any debugging output from that driver ? It would be cool to
see if DMA is at least being kicked properly for small transfers.

It would also be nice to have a clear picture of what "custom spi
driver" you're talking about.

cheers

--=20
balbi

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